Do you have a ShoeZone near you ? Or any shoe shop ? Ask them when there delivery is and ask them to keep them back for you Thats how i got all of mine ...Well i work there so i just took them after shoes had been taken out ! lol
Well, most post offices sell the brown envelope things fairly cheap.
The ones with the bubblewrap inside.
Im sure they would be ok, and properly easier to pack etc.
My heaters were fine when I sent them.
If there the envolopes with the bubble wrap inside,
Just right "FRAGILE" on it, and it should be fine.
Thats what I done.